Construction of the covers of pneumatic tires.



WILLIAM EDGAR MUNTZ, OF LONDON, ENGLAND.

CONSTRUCTION OF THE COVERS OF PNEUMATIC TIRES.

No Drawing.

To all whom it may concern:

Be it known that I, WILLIAM EDGAR MUNTZ, a subject of the King of GreatBritain, and resident of the Royal Automobile Club, 89 to 91 Pall Mall,London, Eng land, late of His Majestys-Public 'Works Department, India,have invented new and useful Improvements in and Relating to theConstruction of the Covers of Pneumatic Tires, of which the following isa specification.

The covers of pneumatic tires are made of several plies of canvascemented together and covered where necessary with wear resistingmaterial to withstand the friction of the road. To keep the wet from thecanvas and to prevent it from rotting, a coating of waterproofingmaterial, generally india rubber, is commonly employed, and it has beensuggested that the canvas, previous to being rubbered, shall beimpregnated with compositions of various descriptions to render itwaterproof, and in one instance rotproof. This treatment however hasbeen found not to be compatible with the vulcanization,

which is necessary when cemented layers of "her.

canvas are used, or when rubber in the cover in any form requires to bevulcanlzed, ow ing to the fact that the materials suggested are liableto mix with the rubber of the tire,

rendering it tacky while the canvas lo'ses more or less its rotproofproperties.

The object of my invention is to provide a rotproof foundation for tirecovers while retaining rubber as a cementing material, as a tread, asbeads or in any other capacity.

The tread need not necessarily be of rub- Any other convenient flexiblemate-' rial, such as leather, may be used, but in every case there willbe rubber for cementing purposes which will require vulcanization torender safe the attachment of the cemented parts.

According to my invention the canvas is treated in such a manner that itbecomes permanently rotproof, and the material employed for rotproofingdoes not mix with or soften the rubber either during vulcani-- zation orrunning. This provides that the canvas, even if exposed to wet-by wearor damage of the rubber coating, will still be preserved from rotting,which is not the case at present. Creosoted wood tar OIl suggested forPatented May 23, 1916.

Application filed July 3, 1913. Serial No. 777,353.

rendering canvas rotproof and the wax and resins proposed for renderingcanvas waterproof are easily miscible with the rubber used and aretherefore unsuitable for tire manufacture owing to the rubber becomingsoftened or tacky and the canvas losing its rotproof or Waterproofproperties during vulcanization or running.

The treatmenLwhich I employ provides either a rotproof surface to thecanvas or transforms the fabric into a rotproof material, therotproofing material employed in both cases being quite insoluble andinert as regards rubber. This treatment which I employ may consist inimpregnating the fabric with cellulose acetate by applying a solution ofcellulose acetate in acetone, trichlorethylene, or other suitablevolatile solvent. Instead of cellulose acetate I may employ other estersof cellulose in solution, avoiding the use of cellulose nitratefor'temperatures exceeding about 220 F. Or the fabric may be treatedwith an acetylating or formylating bath to convert (but not to dissolve)the cellulose partly or entirely into cellulose acetate or formate or amixture of these, preferably employing a low temperature for theconversion of the cellulose. I may here remark that treating cellulose,yarn or woven fabrics with an acetylating bath is not in itself new andI make no claim to such treatment generally. I may, if desired, line thetreated canvas backing with ordinary fabric to provide a smoothinnermost wall, such as of Egyptian cotton or other similar fabric, forthe air tube, so as to prevent undue friction within the tire. In thiscase the ordinary fabric lining may be stitched to the treated canvasand leather or other skin at the same time, or it may be subsequentlysecured thereto by any convenient means.

I wish it to be understood that in my improved tire-cover the rubberused is not for the purpose of excluding water from the interior of thecover, and that the essens tial feature of the invention is the use ofcanvas for the cover which has been made rotproof in the manner aboveexplained. This rotproof canvas lining may be made in as many layers.asdesired. The wearing portion of the cover may also .be formed of aplurality of layers; if desired the outermost layer, forming the treadproper, may

be-cemented or'similarlysecured upoli the said fabricbeing-impregnatedwith esters under layer and in this Way the stitches,of cellulose, whereby it is rendered r0t- Where sewing is used,'nee dnot pass through proof.

the Whole thickness of the tread. WILLIAM EDGAR MU NTZL 5 What I claimand desire to secure by Witnesses:

Letters Patent of the United States is: S. A. NEWTON,

A tire comprising fabric and rubber, the J. PHILLIPS CRAWLEY.

